Sliding clasp fastener

ABSTRACT

A sliding clasp fastener is disclosed which comprises a pair of opposed carrier tapes each carrying along one and the same longitudinal edge a row of fastener elements interengageable to bring the tapes together in closed disposition by the agency of a slider. The elements are formed from a continuous filament material into a spring coil having a coupling head, upper and lower arms and a base. A reinforcing cord is inserted through the coil element row and intimately contacted therewith so as to prevent their relative movements during normal closing and opening operations of the fastener.

[ Dec. 17, 1974 SLIDING CLASP FASTENER [751 Inventor:

[73] Assignee: Yoshida Kogyo Kabushiki Kaisha,

Tokyo, Japan [22] Filed: Oct. 2, 1972 [21] Appl. No.2 294,323

Tadahiro Yoshida, Fujisawa, Japan [30] Foreign Application Priority Data1,529,317 France 24/205.l C 1,940,734 2/1971 Germany 24/205.l C 488,4235/1970 Switzerland 24/205.l C

Primary ExaminerBernard A. Gelak 57] ABSTRACT A sliding clasp fasteneris disclosed which comprisesa pair of opposed carrier tapes eachcarrying along one Oct. 2, 1971 Japan 46-90376 and the same longitudinaledge a row of fastener elements interengageable to bring the-tapestogether in U.S. Cl- C, C closed disposition the agency of a slider Theele- [5 i Il'lt. ments are formed from a continuous filament materialField Of Search C, C, into a pring coil having a coupling head, upperand 24/2 C lower arms and a base. A reinforcing cord is inserted throughthe coil element row and intimately contacted [56] References Citedtherewith so as to prevent their relative movements UNITED STATESPATENTS during normal closing and opening operations of the 3.189.9646/1965 Galonska 24/205.l6 c fastener- FORElGN PATENTS OR APPLICATIONS 3Claims, 4 Drawing Figures 1,253,944 11/1967 Qermany 24/205.l6 C

1 1 Av r r r III i 17 I PAIENI 3.854.174

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SLIDING CLASP FASTENER This invention relates to sliding claspfasteners, more particularly to a sliding clasp fastener of the typewhich has a row of helically wound spring coil elements secured onto alongitudinal edge of a stringer tape.

Generally, the term coil element taken as an individual piecesubstantially comprises a coupling head portion, two arm portions and abase portion merging into an adjacent coil element. It is important tomaintain constant an element-to-element spacing or pitch in its row soas to obtain stable and firm coupling engagement of the elements on thefastener tape. Various attempts have been made to this end. One priorart example is found in a fastener which has a row of coil elements eachhaving a base portion spaced apart from adjacent one and sewn along oneand the same longitudinal marginal edge of a carrier tape together witha stiffening cord inserted through the element row. This type offastener has suffered from the disadvantage that the elements are proneto shift out of position relative to the stiffening cord, with theresult that the pitch of elements in the row is distrubed and thestrength of their coupling engagement is reduced to cause a breakage inthe fastener chain.

Another prior art fastener has been proposed which employs a stiffeningor reinforcing cord having grooves arranged to register with the baseportions of coil elements, so that the elements are secured in placewith their base portions alone anchored in the grooves by means ofclamping threads wound in a direction reverse-to the winding of the coilof elements. Such fastener has been found defective for the purpose ofapplying a row of coil elements to one and the same edge of a carriertape. This is because the reinforcing cord becomes stiff and hard underthe influence of clamping threads, rendering it difficult to pass asewing needle. Since the elements are secured in place only at theirbase portion, their positional stability and coupling strength are notsatisfactory. Furthermore, the operation of winding clamping threadsabout the elements is tedious and time-consuming, and the threads aresusceptible to wear in abrasive contact with aslider.

Whereas, it is the primary object of the present invention to provide animproved sliding clasp fastener of this character which will eliminatethe foregoing disadvantages of the prior art.

It is a more specific object of the invention to provide improvements ina sliding clasp fastener whereby the pitch of elements in a row ismaintained constant and the strength of coupling engagement of elementsis increased.

These objects and features of the invention will appear clear from thefollowing description taken withreference to the accompanying drawingsin which:

FIG. 1 is a plan view on enlarged scale of an important part of asliding clasp fastener embodying the invention;

FIG. 2 is a side view of the same;

FIG. 3 is a cross-sectional view taken on the line III- III of FIG. 1;and

FIG. 4 is a cross-sectional view of an important part of anotherembodiment.

According to the invention, there is provided a sliding clasp fastenerwhich comprises a pair of opposed carrier tapes, a row of fastenerelements mounted on one and the same longitudinal edge of each of saidcarrier tapes, said elements being formed from a continuous filamentinto a helically wound spring coil which has a coupling head, upper andlower arms and a base, adjacent bases of said elements being spaced apredetermined pitch apart, a reinforcing cord inserted longitudinallythrough said row of elements with each of said arms and base partlyembedded in the periphery of said cord, and sewing stitches securingsaid row of elements together with said cord into position on saidcarrier tape.

Referring now to the drawings and FIG. 1 in particular there is shown asliding clasp fastener 10 having a pair of opposed carrier tapes 11 eachcarrying along its one longitudinal edge a row of fastener elements Ewhich are made usually of a continuous plastic filament formed into ahelically wound spring coil. Each individual coil element e consists ofa coupling head 12, an upper arm 13, a lower arm 14 and a base 15. Theelements e in their row E are mounted on the respective carrier tape 11with their base portions 15 spaced a predetermined pitch from adjacentbase portions, as shown. The individual coil element e has an elongatesquare cross-section as seen in FIG. 3. There is provided a reinforcingcord 16 made of a single twisted thermoplastic material such aspolyamide, polyethylene and the like for aligning the row of elements Eand holding the individual elements e in uniformly spacedapart relation.In practice of one aspect of the invention, the cord 16 is insertedlongitudinally through the row of elements E and urged into intimatepressure contact with the inner walls of the upper and lower arms 13, 14and bases 15, respectively of the individual coil elements e during theformation of the latter elements from a starting plastic filament. Theelement row E having the cord 16 thus embraced therein is secured alongone and the same longitudinal edge of the tape 11 by means of sewingstitches 17 in the used manner and thereafter heat-treated so as topermit part of each of the upper and lower arms 13, 14 and base 15 to become affixed to the periphery of the cord 16. Preferably, the elements eof this configuration should be provided with notches or recesses 18 inthe upper arms 13 for retaining the sewn stitches 17 against movementrelative to the elements e. According to another aspect of theinvention, there may be provided peripheral grooves 19 in the cord 16 atpositions corresponding to the pitch of elements e so that the innerwalls of upper and lower arms 13, 14 and base 15 are partly embedded inthe grooves 19 with results similar to the above heat-treatingprocedure.

Turning to FIG. 4 there is shown another sliding clasp fastener which issubstantially identical with the fastener already described and shown inFIGS. 1 3, only with the exception that the element 2 has an eggshapedcross-section. The advantage of this embodiment is that the notches 18referred to above can be dispensed with because the sewing stitches 17due to the peculiar configuration of the elements e are urged toward thebase portions 15 of the elements and thus prevented from shifting out ofposition under normal operating conditions.

Having thus described the invention, it will be apparent to thoseskilled in the art that various changes and modifications may be made inthe specific form and construction illustrated, without departing fromthe scope of the appended claims.

What is claimed is:

1. In a sliding clasp fastener having a pair of opposed stringer tapesand rows of coupling elements mounted on respective stringer tapes, saidcoupling elements being formed as parts on a continuous filament helicalcoil, each element having a coupling head, upper and lower arm portionsand a base portion, the improvement which comprises a reinforcing cordextending longitudinally through the coil defining each row of couplingelements, said reinforcing cord having a heli cal groove disposed forengagement with the coupling elements coil to embed portions thereof insaid groove to maintain a pitch spacing among the coupling ele mentsequivalent to the helical pitch of said groove.

2. The improvement according to claim 1 wherein said groove embeds thebase portion and parts of the upper and lower arm portions of saidcoupling elements.

3. The improvement according to claim 1 including means defining notchesin the upper arm portions of said coupling elements to receive andretain sewing stitches which secure the coupling elements to thestringer tapes.

1. In a sliding clasp fastener having a pair of opposed stringer taPesand rows of coupling elements mounted on respective stringer tapes, saidcoupling elements being formed as parts on a continuous filament helicalcoil, each element having a coupling head, upper and lower arm portionsand a base portion, the improvement which comprises a reinforcing cordextending longitudinally through the coil defining each row of couplingelements, said reinforcing cord having a helical groove disposed forengagement with the coupling elements coil to embed portions thereof insaid groove to maintain a pitch spacing among the coupling elementsequivalent to the helical pitch of said groove.
 2. The improvementaccording to claim 1 wherein said groove embeds the base portion andparts of the upper and lower arm portions of said coupling elements. 3.The improvement according to claim 1 including means defining notches inthe upper arm portions of said coupling elements to receive and retainsewing stitches which secure the coupling elements to the stringertapes.